1. Field of the Invention
The present invention relates to piping and piping assemblies, and more particularly to an assembly that includes an outer casing with one or more smaller insulated flow lines disposed within the outer casing and a plurality of spacers positioned along the flow lines at intervals, the spacers being configured to enable the product flow lines to be pulled through the outer casing during placement.
2. General Background of the Invention
With the advent of deep-water hydrocarbon production from depths exceeding 3,000 feet below mean seal level (msl) one of the methods for installing production flow lines has been to install one or more production flow lines inside an outer carrier or casing pipe. The casing pipe and flow line(s) are pre-welded in long lengths and then the flow line(s) are pulled into the casing pipe by means of a pull winch. The flow line(s) normally has a rigid polyisocyanurite insulation jacket complete encircling the line to keep the hydrocarbon from losing heat. This insulation must be protected from dragging against the casing or it will become torn, dismembered, or ruptured. The insulation jacket must fit snugly against the spacer and sealed in order not to allow heat transfer to take place.
This type of insulated pull-in piping segments are used in both the bottom tow flow line bundle method for installing long land fabricated cased flow line bundle segments that are towed on the ocean bottom to their final installation point and the reel barge method of laying cased flow lines segments that are put together on land, reeled onto the spool barge and then unreeled at the final installation point.
Since this is relatively new technology there have been very few previous projects in the scope of this invention. Previous approaches have required spacers on land and marine cased crossings to use numerous thin short pull spacers to be placed 5-7 feet apart. These spacers were designed to withstand minimal drag and pressure to be exerted on the part and were used to pull a short section of flow line 300 feet or less into a casing pipe.
Several patents have issued that disclosed generally the concept of disposing one pipe or conduit inside of another and wherein spacers form an interface between the inner and outer pipes. The Bond U.S. Pat. No. 2,706,496 discloses a concentric pipe insulator and spacer that includes a plurality of longitudinally extending ribs connected with cable, each of the ribs providing two spaced apart rollers that are provided to contact an outer casing.
In the Cotman U.S. Pat. No. 3,213,889, there is provided a pipe support in the form of a collar that surrounds an inner pipe disposed within an outer pipe.
The Mowell U.S. Pat. No. 3,379,027 discloses a roller supported LNG pipeline that includes an inner pipe having a plurality of rollers extending from the outer surface thereof and wherein the rollers contact the inner wall of an outer casing.
In the Lutchansky U.S. Pat. No. 3,786,379, there is provided a waveguide structure that utilizes roller spring supports for supporting a waveguide in a conduit to simultaneously provide a compliance support and allow free relative longitudinal movement between the waveguide and the conduit. A tension band having a plurality of spring assemblies integrally formed therewith is fastened about eh periphery of the waveguide. Rollers are mounted on the spring assemblies in contact with the conduit to allow free relative longitudinal movement of the waveguide and conduit. The spring assemblies provide a soft compliant support through a range of deflections accommodating the worst expected thermal loading conditions in route bends. Under higher loading the spring assemblies bottom out and provide a stiff support to prevent further radial deflection of the waveguide with respect to the conduit.
A cryogenic fluid transfer line is provided in U.S. Pat. No. 4,233,816 which comprises an interior conduit for passage therethrough of cryogenic fluid, an exterior conduit concentrically spaced about the interior conduit and defining the exterior of the fluid transfer line, an annular heat transfer shield generally concentric with and interjacent to the interior and exterior conduits and including at least one longitudinally extending resilient arcuate member with a longitudinally extending generally arcuate hooking edge, at least one longitudinally extending resilient arcuate member with a longitudinally extending generally arcuate catching edge, where the hooking and catching edge members are interlockingly engageable with each other when the member including the hooking edge is flexed to a smaller arcuate radius, positioned with its hooking edge inboard of the catching edge and then permitted to relax, each set of engaged hooking and catching edges defining a hollow generally cylindrical next having a substantially closed curved surface with each next extending longitudinally substantially the length of the shield, with the shield further including longitudinally extending heat transfer conduits resident within each nest. Radiation shields are provided between the annular heat transfer shield and the interior and exterior conduits.
An underground pipe support device is the subject of U.S. Pat. No. 4,896,701 for supporting an underground pipe or cable within the encasement sleeve of a horizontally bored hole. The support device includes a round collar having two resiliently spaced-apart ends which can be urged together to secure the device to the underground pipe or cable. A plurality of equidistantly spaced-apart and outwardly extending support legs are provided around the circumference of the collar which terminate in an elongate foot having opposing ends inclined inwardly toward the collar. Each foot extends generally parallel to the longitudinal axis of the collar and has a greater length than the longitudinal length of the collar to facilitate placement and support of an underground pipe or conduit within the encasement sleeve of the underground hole.
The Muszynski U.S. Pat. No. 5,069,255 discloses a pipeline casing insulator to support a coated pipe within a tubular metallic casing. The pipeline casing insulator comprises a flexible belt formed of a material that is capable of bonding to an organic resin. A plurality of parallel bar-like runners are formed from an insulative and non-abrasive polymer concrete that is cast onto an outer facing surface of the belt. The belt is preferably a strip of an organic non-woven material. The polymer concrete is preferably a mixture of a thermosetting polymer resin, such as epoxy, polyester or polyrethane, and an aggregate. The aggregate preferably comprises a mixture of substantially incompressible coarse particulate material, such as sand or gravel, and fine filler material, such as calcium carbonate, silica flour, or kaolin. The inner facing surface of the belt preferably has a mastic coating covered by a release paper that can be removed, to allow attachment of the belt to the outer surface of the pipe by circumferentially wrapping the belt around the pipe.
A casing spacer that includes first and second elongated, steel shell members is disclosed in the Eskew U.S. Pat. No. 5,441,082. The casing spacer is comprised of stainless steel or high strength steel with corrosion inhibiting coatings, with each shell member having a semi-circular cross section for engaging and enclosing a carrier pipe within an outer casing. Attached to the outer surface of each of the first and second shell members are one or more adjustable risers for engaging the inner surface of the casing in maintaining the pipe, or pipes, in fixed position within the casing. Each riser includes a runner on its distal end to facilitate positioning of the spacer within the casing. The casing spacer's first and second shell members are securely coupled together by way of flange and nut and bolt combinations along one edge and a hook and eye arrangement along a second, opposed edge. The hook portion of one shell member is easily inserted in the eye portion of the second shell member followed by tightening of the nut and bolt combinations allowing a single worker to easily and quickly install the spacer about a carrier pipe and within a casing.
In the Morris U.S. Pat. No. 5,503,191 a length of elongate material such as rubber hose is supported and guided while being fed along a desired path of travel that extends through the hollow interior of a tubular structure. The tubular structure mounts an array of relatively closely spaced rollers that project into the hollow interior to guide and support the moving length of material. The tubular structure is formed as a "tube within a tube" assembly of "inner" and "outer" tubular members that closely interfit, and that sandwich roller support pins between overlying portions of the inner and outer tubular members. The roller support pins bridge roller positioning holes that are formed through the inner tubular member at an array of spaced locations. The rollers are rotatably mounted by the support pins and project through the positioning holes into the hollow interior of the tubular structure to engage outer surface portions of such elongate material as is being fed through the tubular structure to prevent the moving material from contacting stationary portions of the tubular structure. In preferred practice, a funnel-like roller-carrying end assembly is provided near one end of the tubular structure to define a constricted discharge opening through which the moving material discharges.
A glide tube ring for tube-in-tube systems is disclosed in U.S. Pat. No. 5,592,975. The glide ring tube according to the invention is provided with axially spaced glides running parallel to each other whose material has the lowest possible friction coefficient, especially a plastic, preferably a fiberglass-reinforced polyethylene, polyamide or the like, in which the glide tube ring is attached to the central tube forming a closed ring that centers this tube in the protecting tube, pipe conduit or the like.